Copyright © 2010 Pearson Education, Inc.
C h a p t e r
10
The Endocrine System
PowerPoint® Lecture Slides prepared by Jason LaPres
Lone Star College - North Harris
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
10-1 Homeostasis is preserved through
intercellular communication
Copyright © 2010 Pearson Education, Inc.
The Endocrine System
• The Endocrine System– Regulates long-term processes:
• Growth
• Development
• Reproduction
– Uses chemical messengers to relay information and instructions between cells
Copyright © 2010 Pearson Education, Inc.
The Endocrine System
• Endocrine Communication– Endocrine cells release chemicals
(hormones) into the bloodstream– Alters metabolic activities of many tissues and
organs simultaneously
Copyright © 2010 Pearson Education, Inc.
The Endocrine System
• Target Cells – Are specific cells that possess receptors needed
to bind and “read” hormonal messages
• Hormones– Stimulate synthesis of enzymes or structural
proteins
– Increase or decrease rate of synthesis
– Turn existing enzyme or membrane channel “on” or “off”
Copyright © 2010 Pearson Education, Inc.
10-2 The endocrine systemregulates physiological
processes through the binding of hormones to receptors
Copyright © 2010 Pearson Education, Inc.
The Endocrine System
Figure 10-1
Copyright © 2010 Pearson Education, Inc.
The Endocrine System
Figure 10-1
Copyright © 2010 Pearson Education, Inc.
The Structure of Hormones
• Hormones can be divided into three groups – Amino acid derivatives– Peptide hormones – Lipid derivatives
• Circulate freely or bound to transport proteins
Copyright © 2010 Pearson Education, Inc.
Mechanisms of Hormone Action
• Hormone Receptor – Is a protein molecule to which a particular molecule
binds strongly– Responds to several different hormones– Different tissues have different combinations of
receptors– Presence or absence of specific receptor determines
hormonal sensitivity
Copyright © 2010 Pearson Education, Inc.
Target Cells and Hormones
Figure 10-2
Copyright © 2010 Pearson Education, Inc.
Mechanisms of Hormone Action
• Hormones and Plasma Membrane Receptors– Catecholamines and peptide hormones:
• Are not lipid soluble• Are unable to penetrate plasma membrane• Bind to receptor proteins at the outer surface of the
plasma membrane (extracellular receptors)
Copyright © 2010 Pearson Education, Inc.
Mechanisms of Hormone Action
• Hormones and Plasma Membrane Receptors
– Bind to receptors in plasma membrane
– Cannot have direct effect on activities inside
target cell
– Use intracellular intermediary to exert effects:
• First messenger:
– leads to second messenger
– may act as enzyme activator, inhibitor, or cofactor
– results in change in rates of metabolic reactions
Copyright © 2010 Pearson Education, Inc.
Mechanisms of Hormone Action
• Important Second Messengers – Cyclic-AMP (cAMP):
• Derivative of ATP
– Cyclic-GMP (cGMP): • Derivative of GTP
– Calcium ions
Copyright © 2010 Pearson Education, Inc.
Mechanisms of Hormone Action
• Hormones and Plasma Membrane Receptors
– G Protein:
• Enzyme complex coupled to membrane receptor
• Involved in link between first messenger and second
messenger
• Binds GTP
• Activated when hormone binds to receptor at membrane
surface and changes concentration of second messenger
cyclic-AMP (cAMP) within cell:
– increased cAMP level accelerates metabolic activity within cell
Copyright © 2010 Pearson Education, Inc.
Nonsteroidal Hormones
Figure 10-3a
Copyright © 2010 Pearson Education, Inc.
Mechanisms of Hormone Action
• Hormones and Intracellular Receptors
– Alter rate of DNA transcription in nucleus:
• Change patterns of protein synthesis
– Directly affect metabolic activity and structure
of target cell
– Includes steroids and thyroid hormones
Copyright © 2010 Pearson Education, Inc.
Steroids and Thyroid Hormones
Figure 10-3b
Copyright © 2010 Pearson Education, Inc.
The Control of Endocrine Activity
• Endocrine reflexes can be triggered by
– Humoral stimuli:
• Changes in composition of extracellular fluid
– Hormonal stimuli:
• Arrival or removal of specific hormone
– Neural stimuli:
• Arrival of neurotransmitters at neuroglandular junctions
Copyright © 2010 Pearson Education, Inc.
Hypothalamic Control over Endocrine Function
Figure 10-4
Copyright © 2010 Pearson Education, Inc.
10-3 The bilobed pituitary gland is an endocrine organ that releases nine peptide
hormones
Copyright © 2010 Pearson Education, Inc.
The Pituitary Gland
• Also called hypophysis
• Lies within sella turcica
• Hangs inferior to hypothalamus
– Connected by infundibulum
Copyright © 2010 Pearson Education, Inc.
Pituitary Gland
Figure 10-5
Copyright © 2010 Pearson Education, Inc.
The Hypophyseal Portal System
Figure 10-6
Copyright © 2010 Pearson Education, Inc.
Pituitary Gland
• Two Classes of Hypothalamic Regulatory
Hormones
– Releasing hormones (RH):
• Stimulate synthesis and secretion of one or more hormones at
anterior lobe
– Inhibiting hormones (IH):
• Prevent synthesis and secretion of hormones from the anterior
lobe
• Rate of secretion is controlled by negative
feedback
Copyright © 2010 Pearson Education, Inc.
Pituitary Gland
• Anterior lobe (also called adenohypophysis)– Hormones “turn on” endocrine glands or
support other organs
Copyright © 2010 Pearson Education, Inc.
Feedback Control of Endocrine Secretion
Figure 10-7a
Copyright © 2010 Pearson Education, Inc.
Feedback Control of Endocrine Secretion
Figure 10-7b
Copyright © 2010 Pearson Education, Inc.
Figure 10-8
Copyright © 2010 Pearson Education, Inc.
Pituitary Gland
• Posterior lobe (also called neurohypophysis) – Contains unmyelinated axons of hypothalamic
neurons
– Supraoptic and paraventricular nuclei manufacture:
• Antidiuretic hormone (ADH)
• Oxytocin (OXT)
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
10-4 The thyroid gland liesinferior to the larynx and
requires iodine for hormone synthesis
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
• Lies anterior to thyroid cartilage of larynx
• Consists of two lobes connected by narrow isthmus– Thyroid follicles:
• Hollow spheres lined by cuboidal epithelium
• Cells surround follicle cavity that contains viscous colloid
• Surrounded by network of capillaries that– deliver nutrients and regulatory hormones
– accept secretory products and metabolic wastes
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
• Thyroglobulin (Globular Protein)
– Synthesized by follicle cells
– Secreted into colloid of thyroid follicles
– Molecules contain the amino acid tyrosine
• Thyroxine (T4)
– Also called tetraiodothyronine
– Contains four iodide ions
• Triiodothyronine (T3)
– Contains three iodide ions
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
Figure 10-9a
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
Figure 10-9b
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
• Thyroid-Stimulating Hormone (TSH) – Absence causes thyroid follicles to become
inactive:• Neither synthesis nor secretion occurs
– Binds to membrane receptors– Activates key enzymes in thyroid hormone
production
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
• Thyroid Hormones
– Enter target cells by transport system
– Affect most cells in body
– Bind to receptors in:
• Cytoplasm
• Surfaces of mitochondria
• Nucleus
– In children, essential to normal development of:
• Skeletal, muscular, and nervous systems
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
• Calorigenic Effect – Cell consumes more energy resulting in
increased heat generation– Is responsible for strong, immediate, and
short-lived increase in rate of cellular metabolism
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
The Thyroid Gland
• C (Clear) Cells of the Thyroid Gland– Produce calcitonin (CT):
• Helps regulate concentrations of Ca2+ in body fluids
Copyright © 2010 Pearson Education, Inc.
10-5 The four parathyroidglands, embedded in the
posterior surface of the thyroid gland, secrete parathyroid hormone to elevate blood
calcium levels
Copyright © 2010 Pearson Education, Inc.
Parathyroid Glands
• Embedded in posterior surface of thyroid
gland
• Parathyroid hormone (PTH)
– Produced by chief cells
– In response to low concentrations of Ca2+
Figure 18–12
Copyright © 2010 Pearson Education, Inc.
Parathyroid Glands
Figure 10-11
Copyright © 2010 Pearson Education, Inc.
Parathyroid Glands
• Four Effects of PTH– It stimulates osteoclasts:
• Accelerates mineral turnover and releases Ca2+ from bone
– It inhibits osteoblasts:• Reduces rate of calcium deposition in bone
– It enhances reabsorption of Ca2+ at kidneys, reducing urinary loss
– It stimulates formation and secretion of calcitriol at kidneys:
• Effects complement or enhance PTH
• Enhances Ca2+, PO43- absorption by digestive tract
Figure 18–12
Copyright © 2010 Pearson Education, Inc.
Figure 10-10
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
10-6 The suprarenal glands,consisting of a cortex and a
medulla, cap each kidney andsecrete several hormones
Copyright © 2010 Pearson Education, Inc.
Suprarenal (Adrenal) Glands
• Lie along superior border of each kidney
• Subdivided into
– Superficial suprarenal cortex:• Stores lipids, especially cholesterol and fatty acids
• Manufactures steroid hormones: adrenocortical steroids
(corticosteroids)
– Inner suprarenal medulla:• Secretory activities controlled by sympathetic division of ANS
• Produces epinephrine (adrenaline) and norepinephrine
• Metabolic changes persist for several minutes
Copyright © 2010 Pearson Education, Inc.
Suprarenal Glands
• Mineralocorticoids – For example, aldosterone:
• Stimulates conservation of sodium ions and elimination of potassium ions
• Increases sensitivity of salt receptors in taste buds
– Secretion responds to:• Drop in blood Na+, blood volume, or blood pressure
• Rise in blood K+ concentration
Copyright © 2010 Pearson Education, Inc.
Suprarenal Glands
• Glucocorticoids
– For example, cortisol (hydrocortisone) with
corticosterone:
• Liver converts cortisol to cortisone
– Secretion regulated by negative feedback
– Has inhibitory effect on production of
• Corticotropin-releasing hormone (CRH) in hypothalamus
• ACTH in adenohypophysis
Copyright © 2010 Pearson Education, Inc.
Suprarenal Glands
• Produces androgens under stimulation by ACTH
Copyright © 2010 Pearson Education, Inc.
Suprarenal Glands
Figure 10-12
Copyright © 2010 Pearson Education, Inc.
Suprarenal Glands
• Suprarenal Medulla– Contains two types of secretory cells:
• One produces epinephrine (adrenaline):– 75% to 80% of medullary secretions
• The other produces norepinephrine (noradrenaline):– 20% to 25% of medullary secretions
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
10-7 The pineal gland, attached to the third ventricle,
secretes amelatonin
Copyright © 2010 Pearson Education, Inc.
Pineal Gland
• Lies in posterior portion of roof of third ventricle
• Contains pinealocytes – Synthesize hormone melatonin
Copyright © 2010 Pearson Education, Inc.
Pineal Gland
• Functions of Melatonin – Inhibiting reproductive functions– Protecting against damage by free radicals– Setting circadian rhythms
Copyright © 2010 Pearson Education, Inc.
10-8 The endocrine pancreasproduces insulin and
glucagon, hormones that regulate blood glucose levels
Copyright © 2010 Pearson Education, Inc.
Pancreas
• Lies between– Inferior border of stomach– And proximal portion of small intestine
• Contains exocrine and endocrine cells
Copyright © 2010 Pearson Education, Inc.
Pancreas
• Endocrine Pancreas
– Consists of cells that form clusters known as
pancreatic islets, or islets of Langerhans:
• Alpha cells produce glucagon
• Beta cells produce insulin
Copyright © 2010 Pearson Education, Inc.
Pancreas
Figure 10-13
Copyright © 2010 Pearson Education, Inc.
Pancreas
• Blood Glucose Levels – When levels rise:
• Beta cells secrete insulin, stimulating transport of glucose across plasma membranes
– When levels decline: • Alpha cells release glucagon, stimulating glucose
release by liver
Copyright © 2010 Pearson Education, Inc.
Figure 10-14
Copyright © 2010 Pearson Education, Inc.
10-9 Many organs have secondary endocrine functions
Copyright © 2010 Pearson Education, Inc.
Endocrine Tissues of Other Systems
• Intestines (digestive system)
• Kidneys (urinary system)
• Heart (cardiovascular system)
• Thymus (lymphoid system and immunity)
• Gonads (reproductive system)
Copyright © 2010 Pearson Education, Inc.
Endocrine Tissues of Other Systems • Intestines
– Produce hormones important to coordination of digestive activities
• Kidneys– Produce the hormones calcitriol and erythropoietin– Produce the enzyme renin
Copyright © 2010 Pearson Education, Inc.
Endocrine Tissues of Other Systems
• Heart
– Produces natriuretic peptides (ANP and BNP):
• When blood volume becomes excessive
• Action opposes angiotensin II
• Resulting in reduction in blood volume and blood pressure
• Thymus
– Produces thymosins (blend of thymic hormones):
• That help develop and maintain normal immune defenses
Copyright © 2010 Pearson Education, Inc.
Endocrine Tissues of Other Systems
• Testes (Gonads)– Produce androgens in interstitial cells:
• Testosterone is the most important male hormone
– Secrete inhibin in nurse (sustentacular) cells:
• Support differentiation and physical maturation of sperm
Copyright © 2010 Pearson Education, Inc.
Endocrine Tissues of Other Systems
• Ovaries (Gonads)– Produce estrogens:
• Principle estrogen is estradiol
– After ovulation, follicle cells:• Reorganize into corpus luteum• Release estrogens and progestins, especially
progesterone
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Endocrine Tissues of Other Systems
• Adipose Tissue Secretions – Leptin:
• Feedback control for appetite• Controls normal levels of GnRH, gonadotropin
synthesis
– Resistin:• Reduces insulin sensitivity
Copyright © 2010 Pearson Education, Inc.
10-10 Hormones interactto produce coordinatedphysiological responses
Copyright © 2010 Pearson Education, Inc.
Hormone Interactions
• Antagonistic (opposing) effects
• Synergistic (additive) effects
• Permissive effects: one hormone is necessary for
another to produce effect
• Integrative effects: hormones produce different
and complementary results
Copyright © 2010 Pearson Education, Inc.
Hormones and Growth
• Growth Hormone (GH) – In children:
• Supports muscular and skeletal development
– In adults:• Maintains normal blood glucose concentrations• Mobilizes lipid reserves
Copyright © 2010 Pearson Education, Inc.
Hormones and Growth
• Thyroid Hormones – If absent during fetal development or for first
year:• Nervous system fails to develop normally• Mental retardation results
– If T4 concentrations decline before puberty:• Normal skeletal development will not continue
Copyright © 2010 Pearson Education, Inc.
Hormones and Growth
• Insulin – Allows passage of glucose and amino acids across
plasma membranes
• Parathyroid Hormone (PTH) and calcitriol– Promote absorption of calcium salts for deposition in
bone– Inadequate levels cause weak and flexible bones
Copyright © 2010 Pearson Education, Inc.
Hormones and Growth
• Reproductive Hormones
– Androgens in males, estrogens in females
– Stimulate cell growth and differentiation in
target tissues
– Produce gender-related differences in:
• Skeletal proportions
• Secondary sex characteristics
Copyright © 2010 Pearson Education, Inc.
Hormones and Stress
• General Adaptation Syndrome (GAS) – Also called stress response– How body responds to stress-causing factors– Is divided into three phases:
1. Alarm phase
2. Resistance phase
3. Exhaustion phase
Figure 18–18
Copyright © 2010 Pearson Education, Inc.
Hormones and Stress
Figure 10-15
Copyright © 2010 Pearson Education, Inc.
Hormones and Stress
Figure 10-15
Copyright © 2010 Pearson Education, Inc.
Hormones and Stress
Figure 10-15
Copyright © 2010 Pearson Education, Inc.
Hormone Interactions
• Hormones and Behavior
– Can alter intellectual capabilities, memory, learning,
and emotional states
– Affect behavior when endocrine glands are over-
secreting or under-secreting
• Aging
– Causes few functional changes
– Decline in concentration of:
• Growth hormone
• Reproductive hormones
Copyright © 2010 Pearson Education, Inc.
10-11 Extensive integrationoccurs between the endocrine
system and other body systems
The Endocrine System in Perspective
Functional Relationships Between the Endocrine System and Other Systems
Copyright © 2010 Pearson Education, Inc.
The Integumentary System protects
superficial endocrine organs;
epidermis synthesizes vitamin D3
The Endocrine System’s sex
hormones stimulate sebaceous
glands, influence hair growth, fat
distribution, and apocrine sweat
glands; PRL stimulates development
of mammary glands; suprarenal
hormones alter dermal blood flow,
stimulate release of lipids from
adipocytes; MSH stimulates
melanocytes
The Integumentary System
Copyright © 2010 Pearson Education, Inc.
The Skeletal System protects
endocrine organs, especially in the
brain, chest, and pelvic cavity
The Endocrine System regulates
skeletal growth: PTH and calcitonin
mobilize calcium; sex hormones
speed growth and close epiphyseal
cartilages at puberty, and help
maintain bone mass in adults
The Skeletal System
Copyright © 2010 Pearson Education, Inc.
The Muscular System
The Muscular System provides
protection for some endocrine
organs
The Endocrine System adjusts
Muscle metabolism, energy
production, and growth; regulates
calcium and phosphate levels in
body fluids; speeds skeletal
muscle growth
Copyright © 2010 Pearson Education, Inc.
The Nervous System
The Nervous System’s hormones
control secretions by the pituitary,
other endocrine organs, and suprarenal
medullae; secretes ADH and oxytocin
The Endocrine System’s hormones
affect neural metabolism; help regulate
fluid and electrolyte balance;
reproductive hormones influence
CNS development and behaviors
Copyright © 2010 Pearson Education, Inc.
The Cardiovascular System
The Cardiovascular System’sVessels distribute hormonesthroughout the body; heart secretesANP
The Endocrine System’s hormoneEPO regulates production of RBCs;several hormones elevate bloodpressure; Epinephrine elevates heartrate and contraction force
Copyright © 2010 Pearson Education, Inc.
The Lymphoid System
The Lymphoid System’s lymphocytesdefend against infection and, withother WBCs, assist in repair afterInjury
The Endocrine System’s hormoneshave anti-inflammatory effects(glucocorticoids),stimulate development oflymphocytes (thymosins), and affectimmune function
Copyright © 2010 Pearson Education, Inc.
The Respiratory System
The Respiratory System providesoxygen and eliminates carbonDioxide generated by endocrineCells
The Endocrine System’shormones Epinephrine and NE stimulaterespiration and dilaterespiratory passageways
Copyright © 2010 Pearson Education, Inc.
The Digestive System
The Digestive System providesnutrients to endocrine cells; Pancreassecretes insulin and glucagon; liverproduces angiotensinogen
The Endocrine System’s hormones Epinephrine and NE constrict sphincters and depress activity along digestive tract; digestive tract hormones coordinate secretions along tract
Copyright © 2010 Pearson Education, Inc.
The Urinary System
The Urinary System’s kidney cells(1) release renin and EPO when localblood pressure declines and(2) produce calcitriol
The Endocrine System’s hormones(aldosterone, ADH, and ANP) adjustfluid and electrolyte reabsorption inkidneys
Copyright © 2010 Pearson Education, Inc.
The Reproductive System
The Reproductive System’s steroidsex hormones and inhibin suppresssecretion in hypothalamus andpituitary
The Endocrine System’s hypothalamicand pituitary hormones regulatesexual development and function;oxytocin stimulates contractions ofthe uterus and mammary glands
Copyright © 2010 Pearson Education, Inc.